JPH06200410A - Production of high-molecular weight polyester yarn - Google Patents

Abstract

PURPOSE:To produce yarn having excellent mechanical properties such as tensile strength from a high-molecular weight polyethylene terephthalate-based polyester. CONSTITUTION:A high-molecular weight polyethylene terephthalate-based polyester having >=1.2 intrinsic viscosity is dissolved in a p-chlorophenol solvent alone or a mixed solvent of p-chlorophenol and a chlorine-based solvent to prepare a spinning dope, which is subjected to wet or a semidry semiwet spinning by using a coagulating bath such as ethylene glycol and optionally drawn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester fiber having excellent mechanical properties by spinning a high molecular weight polyester in a wet or semi-dry semi-wet state.

[0002]

2. Description of the Related Art Polyester fiber, especially polyethylene terephthalate fiber, is a material widely used not only for clothing but also for industry because of its well-balanced physical properties and good spinnability / drawability. Particularly, the high-strength polyester fiber is useful for various industrial material applications including tire applications.

For polyester fibers, the melt-spinning method, which is economically advantageous, is usually adopted. In order to develop the high strength required for industrial applications, melt spinning is performed using polyester having a high degree of polymerization, Then, it is common to carry out stretching at a high magnification. However, there is an upper limit to the melt viscosity of a polymer to which melt spinning can be applied, and it is difficult to obtain a substantially stretchable raw yarn by a spinning process with a polyester having an intrinsic viscosity of 1.2 or more. As a result, melt spinning has a strength of 1
It has been difficult to industrially produce fibers exceeding 0 g / d.

On the other hand, there is a method in which a polyester having a higher degree of polymerization is made into fibers by dissolving the polyester in an organic solvent and spinning it.
No. 07616, JP-A-62-30024 and JP-A-4-73212. However, JP-A-6
The methods of 1-207616 and JP-A-4-73212 use dichloroacetic acid and hexafluoroisopropanol as solvents, respectively. The former is strongly acidic and the handling and spinning device materials are limited, while the latter is Since a large amount of extremely expensive solvent is used, there is a problem in industrial practical use. In addition, JP-A-62-30024
The method of No. 1 uses nitrobenzene as a solvent, but it requires heating to 200 ° C. or higher to dissolve the polymer.
It is difficult to avoid lowering the degree of polymerization during dissolution.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to form a high molecular weight polyester into a fiber by a practical wet or semi-dry semi-wet process to obtain a strength of 10 g which cannot be obtained by conventional melt spinning. The object of the present invention is to provide a method for producing a polyester fiber having an excellent mechanical property exceeding / d.

[0006]

According to the present invention, the intrinsic viscosity is
Characteristic is that a polyester having 1.2 or more substantially ethylene terephthalate units is dissolved in p-chlorophenol or a mixed solvent of p-chlorophenol and another chlorinated solvent, and wet or semi-dry semi-wet spinning is performed. And a method for producing high molecular weight polyester fiber.

The polyester to be used in the present invention consists essentially of ethylene terephthalate units, and contains terephthalic acid as a main acid component and ethylene glycol as a main glycol component. The term "mainly" as used herein means that the content is more than 60 mol%, preferably more than 80 mol%. Therefore, less than 40 mol% and preferably less than 20 mol% of other acid component and other diol component (third component) may be contained.

As the third component which can be copolymerized with the polyester as the starting material in the method of the present invention, aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and diphenyletherdicarboxylic acid, oxalic acid, malonic acid, Succinic acid, adipic acid,
Aliphatic dicarboxylic acids such as sebacic acid and decane dicarboxylic acid, hexahydroterephthalic acid, decalin dicarboxylic acid, tetralin dicarboxylic acid and the like,
Oxyacids such as glycolic acid and p-hydroxybenzoic acid,
Trimethylene glycol, propylene glycol, 1,
Aliphatic diols such as 4-butanediol, 1,3-butanediol, neopentyl glycol and 1,6-hexanediol, alicyclic diols such as cyclohexanedimethanol and tricyclodecanedimethanol, bisphenol A, bisphenol S, Aromatic diols such as tetrabromobisphenol, hydroquinone and dihydroxydiphenyl are exemplified.

However, in the present invention, a polyethylene terephthalate homopolymer is particularly preferred.

In the polyester of the present invention, if necessary, stabilizers such as ultraviolet absorbers, antioxidants, plasticizers,
Lubricants, flame retardants, release agents, pigments and the like can be added as appropriate.

The polyester used in the method of the present invention is 3
It is necessary that the intrinsic viscosity measured with a p-chlorophenol / 1,1,2,2-tetrachloroethane mixed solvent (40/60 weight ratio) at 5 ° C is 1.2 or more. When the intrinsic viscosity is less than 1.2, the molecular weight is insufficient and the desired polyester fiber having excellent mechanical properties cannot be obtained. The intrinsic viscosity is preferably 1.5 or more, more preferably 1.8 or more.

The high molecular weight polyester having a high intrinsic viscosity can be obtained by a conventionally known solid-state polymerization method.

The method for producing the polyester fiber of the present invention comprises:
A high-molecular-weight polyester is dissolved in a single solvent of p-chlorophenol or a mixed solvent of p-chlorophenol and another chlorinated solvent to prepare a spinning stock solution, which is formed into fibers by wet spinning or semi-dry semi-wet spinning. Is.

Here, the "other chlorinated solvent" means 1,1,
2,2-Tetrachloroethane, chloroform and dichloromethane are used alone or as a mixture. Of these, 1,1,2,2-tetrachloroethane is preferably used alone because of the solubility of the polymer.

The mixing ratio of p-chlorophenol and chloro solvent is preferably such that p-chlorophenol is 20 to 100% by weight and chloro solvent is 80 to 0% by weight. A more preferable composition range is p-
Chlorophenol is 40 to 100% by weight and chlorinated solvent is 60 to 0% by weight.

The polymer concentration of the spinning dope used in the method of the present invention is preferably 5 to 50% by weight. Polymer concentration is 5
If it exceeds 0% by weight, complete dissolution of the polymer becomes difficult.
If it is less than 5% by weight, the viscosity of the spinning dope is too low and the spinnability tends to decrease.

The stock solution for spinning thus prepared is discharged from a spinning nozzle by using an extruder and then introduced into a coagulation bath to form yarns, and gel fibers can be obtained.
As a spinning method, either a complete wet method in which a spinning dope is discharged in a coagulation bath or a semi-dry / semi-wet method in which a spinning solution is once discharged into the air and then introduced into a coagulation bath can be adopted. At this time, 60% of ethylene glycol is used as the coagulation bath liquid.
As described above, by using a liquid containing 80% or more, it is possible to form a gel fiber that is homogeneous, excellent in transparency, and extremely highly stretchable.

Other components that can be added to ethylene glycol as the bath liquid of the coagulation bath include methanol, ethanol,
Acetone, water, isobutyl alcohol, n-butyl alcohol, propylene glycol, glycerin, tetrachloroethane, chloroform, dichloromethane and the like can be used. The temperature of the coagulation bath is not particularly limited, but 2
0-100 degreeC is used suitably.

The gel fiber thus obtained can be stretched in a single stage or multiple stages in an ethylene glycol bath or in air. The stretching temperature is not particularly limited, but 2
0-100 degreeC is used suitably.

The gel fiber can be made into a dense solid fiber by removing the solvent in an ethylene glycol bath and then washing it with water to remove the ethylene glycol and the residual solvent, and drying it. it can. The solid fiber after drying (hereinafter referred to as dry yarn) can be drawn and heat-treated in the same manner as the polyester fiber obtained by ordinary melt spinning.

At this time, it is preferable to further draw the dry yarn after drawing the gel fiber. The total draw ratio is preferably 5 times or more, more preferably 6 times or more. Here, the total draw ratio is the product of the draw ratio of the gel fiber and the draw ratio of the dry yarn. Thus,
By appropriately selecting the stretching conditions, it is possible to obtain a polyester fiber having a high tensile strength exceeding 10 g / d, which has been difficult to industrially produce by a conventional method.

[0022]

As described above, according to the method of the present invention, a polyester having a high degree of polymerization can be spun by a wet method or a semi-dry semi-wet method while preventing a decrease in the molecular weight and in a general-purpose solvent system. By forming a gel fiber and expressing the high degree of fiber orientation by stretching the gel fiber and the dry yarn at a high ratio, it is possible to produce a polyester fiber having remarkably excellent mechanical properties.

The high molecular weight polyester fiber obtained by the method of the present invention has excellent mechanical properties,
It can be widely used for industrial materials including reinforcing materials such as belts.

[0024]

EXAMPLES Next, examples of the present invention will be described in detail. However, the following examples do not limit the present invention. The physical properties used in the present invention are measured by the following methods.

(A) Intrinsic viscosity It was measured at 35 ° C. using p-chlorophenol / 1,1,2,2-tetrachloroethane mixed solvent (40/60 weight ratio).

(B) Tensile Properties Tensile strength, elongation at break, and Young's modulus of the fiber were determined by subjecting a single fiber having a test length of 25 mm to a constant-speed tensile test at a tensile speed of 100% per minute.

[0027]

Example 1 Polyethylene terephthalate having an intrinsic viscosity of 2.37 obtained by solid phase polymerization in a nitrogen stream at 240 ° C. was mixed with p-chlorophenol and 1,1,2,2-tetrachloroethane mixed solvent (40 / 60 weight ratio) to obtain a solution having a polymer concentration of 20% by weight.
This polymer solution was mixed with a blanker type extruder at 50
Extruded at 50 ° C. into a 50 ° C. ethylene glycol bath to obtain gel fibers. At this time, the spinning nozzle has a diameter of 0.15 mm,
The discharge linear velocity was 2 m / min.

The gel fiber thus obtained was washed with boiling water and dried at a constant length on a drying roller, then it was quadrupled at 120 ° C., and further 2 times.
It was stretched 1.5 times at 00 ° C.

The tensile strength of the drawn fiber thus obtained was 10.5 g.
/ D, Young's modulus was 100 g / d. The intrinsic viscosity of the fiber was 2.10.

[0030]

Example 2 A gel fiber was prepared in the same manner as in Example 1, the gel fiber was stretched 5.0 times in ethylene glycol, washed with boiling water, and then dried on a drying roller at a fixed length.
The obtained dried yarn was further stretched 1.3 times at 200 ° C.

The tensile strength of the obtained drawn fiber is 11.0 g.
/ D, Young's modulus was 130 g / d. The intrinsic viscosity of the fiber was 2.15.

[0032]

Example 3 A polymer solution prepared by the same method as in Example 1 was once discharged into the air using a plunger type extruder and then introduced into an ethylene glycol bath at 50 ° C. to be solidified.

After washing the obtained gel fiber in boiling water, it was dried at a constant length on a drying roller, and it was 4 times at 120 ° C., and further 20 times.
It was stretched 1.6 times at 0 ° C.

The tensile strength of the obtained drawn fiber is 10.7.
The Young's modulus was 110 g / d. The intrinsic viscosity of the fiber was 2.0.

Claims (5)

[Claims] 1. A wet or semi-dry solution in which p-chlorophenol or a mixed solvent of p-chlorophenol and another chlorinated solvent is dissolved in a polyester having an intrinsic viscosity of 1.2 or more and substantially consisting of ethylene terephthalate units. A method for producing a high molecular weight polyester fiber, which comprises performing semi-wet spinning. 2. The method for producing a high molecular weight polyester fiber according to claim 1, wherein a liquid bath containing 60% by weight or more of ethylene glycol is used as a coagulating bath when performing wet or semi-dry semi-wet spinning. 3. The method for producing a high molecular weight polyester fiber according to claim 1 or 2, wherein the spinning dope has a polymer concentration of 5 to 50% by weight. 4. The gel fiber taken out from the coagulation bath is stretched in that state at a total draw ratio of 5 times or more in one step or two steps or more, according to claim 1, 2 or 3. Method for producing high molecular weight polyester fiber. 5. The gel fiber taken out from the coagulation bath is washed with water and dried, and then stretched at a total draw ratio of 5 times or more in one step or two steps or more.
The method for producing a high molecular weight polyester fiber as described in 1.